Fast occlusion processing for a polygon-based computer-generated hologram using the slice-by-slice silhouette method.

In a polygon-based computer-generated hologram (CGH), the three-dimensional (3D) model is represented as a polygon, which consists of numerous small facets. Lighting effect, material texture, and surface property can be included in the polygonal model, which enables polygon-based CGH to realize high-fidelity 3D display. On the other hand, the occlusion effect is an important depth cue for 3D display. In polygon-based CGH, however, occlusion processing is difficult and time-consuming work. In this paper, we proposed a simple and fast occlusion processing method, the slice-by-slice silhouette (S3) method, for generating the occlusion effect in polygon-based CGH. In the S3 method, the polygonal model is sliced into multiple thin segments. For each segment, a silhouette mask is generated and located at the backside of the segment. The incident light is first shaded by the mask and superimposes on the light emitted from the facets of the evaluated segment. In this way, every segment can be processed sequentially to get the resulting object light. Our experimental result demonstrates that the S3 method can generate a high-definition hologram with qualified occlusion effect. The computing complexity of the S3 method is lower than that of previous methods. In addition, the S3 method can be parallelized easily, and thus can be further speeded up by applying a parallel computing framework, such as multi-core CPU or GPU.

Clinical Observation of Berberine in Intervening Insulin Resistance of Polycystic Ovary Syndrome / 广州中医药大学学报

Objective To evaluate the clinical efficacy of berberine for the treatment of insulin resistance (IR) in women with polycystic ovary syndrome (PCOS).Methods Sixty PCOS-IR women were randomized into treatment group and control group,30 cases in each group.At the end of the trial,26 cases in the treatment group (4 cases dropped out) and 29 cases in the control group (one case dropped out) completed the trial.The treatment group was treated with berberine orally,and the control group was treated with metformin orally,the treatment for the two groups lasting 3 months.Before and after treatment,we observed the parameters of body mass index (BMI),homeostasis model of assessment for insulin resistance index (HOMA-IR),fasting plasma glucose (FPG),fasting insulin (FINS),2-hour postprandial glucose after oral glucose tolerance test (OGTT2hPG) and 2-hour postprandial insulin after OGTT (OGTT2hINS),blood lipid levels of total cholesterol (TC),triglyceride (TG),low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C),and sexual hormones of follicle-stimulating hormone (FSH),luteotropic hormone (LH),testosterone (T) and LH/FSH ratio.Results BMI,HOMA-IR,TC,TG and LDL-C of the two groups were decreased after treatment (P ＜ 0.05 or P ＜ 0.01 compared with those before treatment),but the differences between the two groups were insignificant(P ＞ 0.05).Serum levels of T and LH as well as LH/FSH ratio in the treatment group were also decreased (P ＜ 0.05 or P ＜ 0.01 compared with those before treatment and those in the control group after treatment).Conclusion Berberine can improve HOMA-IR,decrease serum sexual hormones levels,and regulate the blood metabolism in PCOS-IR women,and its effect is similar to that of metformin.

Uremic tumoral calcinosis in patients on peritoneal dialysis: clinical, radiologic, and laboratory features.

BACKGROUND: Uremic tumoral calcinosis (UTC) has been analyzed in uremic patients on hemodialysis, but little is known about UTC in peritoneal dialysis (PD). In this study, we aimed to characterize UTC in uremic patients on PD. METHODS: We retrospectively reviewed uremic patients on PD who developed UTC over a 9-year period. Clinical, radiologic, and laboratory features; treatments; and outcomes in those patients were assessed. One of the patients (case 7) is described as a case example. RESULTS: The study enrolled 7 patients with a mean age of 41 years. Mean time from PD to UTC was 45.3 months. All patients were anuric but adequately dialyzed. Cardinal symptoms were local tenderness and limited range of joint motion. Lesions were mostly multifocal (n=6) and predominantly involved shoulders, hands, feet, hips, and wrists. Metatarsophalangeal joint UTC was misdiagnosed as tophaceous gout in 2 patients. Main laboratory findings were hyperphosphatemia (7.9 ± 0.8 mg/dL), high Ca×P product [>65 mg(2)/dL(2) (range: 81.1 ± 11.5 mg(2)/dL(2))], secondary hyperparathyroidism (SHPT) with various levels of intact parathyroid hormone (iPTH: 592.2 ± 315.2 pg/mL; <250 pg/mL in 2 patients). Medical treatments for UTC included P restriction, non-Ca-based phosphate binders, and adequate dialysis with low-Ca dialysate, but all treatments were ineffective. Parathyroidectomy (n=3) can partially ameliorate UTC, but only 1 patient (case 7), who had extremely high iPTH (1085 pg/mL), manifested hungry bone syndrome (HBS) and had remarkable resolution of UTC. By contrast, in patients who underwent renal transplantation (n=3), UTC completely resolved by about 1 year after surgery. CONCLUSIONS: Uremic tumoral calcinosis develops in anuric PD patients with uncontrolled hyperphosphatemia; it is usually multifocal, occurring around the weight-bearing joints or overused smaller joints. Aggressive medical therapy alone is ineffective, and parathyroidectomy appears to be unsatisfactory except in the presence of severe SHPT with postoperative HBS.

An unusual cause of thyrotoxic periodic paralysis: triiodothyronine-containing weight reducing agents.

Thyrotoxic periodic paralysis resulting from exogenous thyroid hormone administration (thyrotoxicosis factitia) has been rarely reported. We describe a 23-year-old man who presented with limbs paralysis upon awakening in the morning. Pertinent history revealed that he took drugs containing triiodothyronine (64 mug) and propranolol (40 mg) twice daily for weight reduction in the past month and discontinued these drugs 3 days before admission. Physical examination showed systolic hypertension (160/76 mm Hg), relative tachycardia (98 bpm), and symmetrical flaccid paralysis of all extremities. The most striking laboratory finding was severe hypokalemia (1.6 mmol/L) with low urinary potassium excretion and normal blood acid-base status, suggesting acute potassium shifting into cells. Approximately, 174 mmol of potassium chloride was administrated to restore his muscle strength within 12 hours, but rebound hyperkalemia (6.1 mmol/L) developed upon recovery. Despite normal serum free triiodothyronine and thyroxine levels, the suppressed concentration of thyroid stimulating hormone indicated hyperthyroidism. The low radioiodine uptake (4%) and serum thyroglobulin level (2 ng/mL) were consistent with thyrotoxicosis factitia. This is the first reported case of exogenous triiodothyronine-induced thyrotoxic periodic paralysis, which may have been precipitated by the withdrawal of propranolol.